Flexible electrochromic materials based on CNT/PDA hybrids.

Materials that change color in response to external stimuli can cater to diverse applications from sensing to art. If made flexible, stretchable and weavable, they may even be directly integrated with advanced technologies such as smart textiles. A new class of engineered composite based on polydiacetylene (PDA) functionalized carbon nanotubes (CNT) shows tremendous potential in this regard. While the inherent multi stimuli chromatic response of the polymer (blue to red) is retained, the underlying conducting CNTs invoke electrochromism in PDA. Further, the fiber form factor of dry-spun CNT yarns facilitate direct weaving of large scale electrochromic fabrics, where current flow and thus color change can be accurately controlled. This review summarizes the fundamental aspects of CNT yarns and PDAs, focusing especially on their interaction chemistry which results in the scientifically and commercially appealing electrochromic transition in these hybrids.